I've been training the Super Gravitron for 4 months and I only got ≈11,5 sec., but I see everyone getting >30 sec.!

You need to learn what kinds of patterns there are and what's the best way to approach most of them. If your record is barely more that 10 seconds then it probably means that you have no real idea of what you're doing and you're just "trying to survive" which is far from enough for a gave as punishing as the SG!